The present invention relates to a metering valve for automatic fluid metering devices, particularly for industrial ink and paint.
Automatic fluid metering devices are known wherein a supporting structure presents a number of metering valves, each presenting a delivery way, a recirculating way, and a supply nozzle.
Each valve is movable in relation to the supporting structure between a first idle position wherein the nozzle is closed and all the incoming fluid is recirculated, and an operating position wherein the valve is connected to a regulating device for so opening the valve as to feed part of the incoming fluid out through the nozzle.
Gradual opening of the valve results in a variation in the total section of the fluid passage and hence in the hydraulic resistance of the valve, so that any variation in the supply pressure of the valve results in a sharp variation in supply by the nozzle even with no change in the section of the fluid passage.
Moreover, gradual opening of the valve results in a sharp variation in pressure inside the valve itself.